WO2019115083A1

WO2019115083A1 - Curable fluoroelastomers having low swelling tendency

Info

Publication number: WO2019115083A1
Application number: PCT/EP2018/079808
Authority: WO
Inventors: Arthur Lanziner
Original assignee: Carl Freudenberg Kg
Priority date: 2017-12-15
Filing date: 2018-10-31
Publication date: 2019-06-20
Also published as: EP3724271A1; US20240117175A1; DE102017011642A1; US20210171755A1; CN111465649A

Abstract

The invention relates to a curable fluoroelastomer composition having low swelling tendency, comprising: A) a curable fluoroelastomer; B) a curing system; and C) 0.1 wt.-% to 30 wt.-% of a nitrogen-containing polymer, selected from polyamide, polyimide, mixtures and/or copolymers thereof, each relative to the total weight of fluoroelastomer and nitrogen-containing polymer, the nitrogen-containing polymer being present in particulate form of an average particle size in the range of 0.15 to 70 µm and/or in fiber form having an average fiber diameter in the range of 0.15 to 70 µm.

Description

Curable fluoroelastomers with low swelling tendency

description

This invention relates to low durometer curable fluoroelastomers

Quellungsneigung.

Fluoroelastomers (FKM) are characterized by excellent physical and chemical properties such as high heat resistance, oil resistance and chemical resistance and are therefore widely used as sealing materials. Examples of fluoroelastomers include copolymers comprising units of vinylidene fluoride (VF 2) and units of at least one other copolymerizable fluorine-containing monomer, such as e.g. Hexafluoropropylene (HFP), tetrafluoroethylene (TFE), chlorotrifluoroethylene (CTFE), vinyl fluoride (VF), and fluorovinyl ethers such as perfluoro (alkyl vinyl ether) (PAVE). Specific examples of PAVE include perfluoro (methyl vinyl ether),

Perfluoro (ethyl vinyl ether) and perfluoro (propyl vinyl ether).

To improve their mechanical properties, such as tensile strength or elongation, elastomers are cured, i. vulcanized or crosslinked. In the case of fluoroelastomers, this is generally done by mixing

uncured polymer (ie, fluoroelastomer gum) with a polyfunctional curing agent and heating the resulting mixture. Here, a chemical reaction of the curing agent with active sites along the Polymer skeleton or side chains instead, creating a networked

Polymer composition is obtained with a three-dimensional network structure.

Typical curing agents for fluoroelastomers include a free radical generator such as e.g. an organic peroxide in combination with a multifunctional crosslinking coagulation. Typically, a metal oxide is added to this combination to enhance the curing reaction (i.e., both the

Curing intensity as well as the cure rate). A disadvantage of the use of a metal oxide, however, is that the cured fluoroelastomers obtainable in this case, if they are for a long time or at elevated temperatures organic acids or acidic media

Hydrocarbon additions (fuel, oil) are exposed, a very high volume swelling (eg., 20-200 vol.%) Have, resulting in

Seal failure may result. This swelling can be prevented or

at least minimized by eliminating metal oxides from the compositions. However, this leads to a deterioration of

High temperature properties of the elastomer, in particular the tensile strength at high temperatures. Further, fluoroelastomeric materials in which metal oxides are eliminated from the compositions exhibit a markedly increased mold-soiling tendency, which is considered to deteriorate

Processing property is valued.

WO 2014088919 (A1) describes a curable

Fluoroelastomer composition comprising: A) a peroxide-curable fluoroelastomer; B) an organic peroxide; C) a multifunctional coagent; and D) from 0.5% to 30% by weight of polyamide, based on the total weight of fluoroelastomer and polyamide. The production of

The fluoroelastomer composition comprises the following steps: A) providing a peroxide-curable fluoroelastomer; B) providing a polyamide with a melting temperature or a glass transition temperature; C) mixing the peroxide curable fluoroelastomer with the polyamide at a temperature greater than the melting temperature or glass transition temperature of the polyamide, whichever is greater, D) cooling the polymer blend to solidify the polyamide; and E) adding a peroxide curative and a multifunctional coagent to the

Polymer mixture at a temperature lower than that

Melting temperature or glass transition temperature of the polyamide, whichever is lower.

With the described Fierstellungsverfahren the polyamide is in

molten form incorporated into the fluoroelastomer. Flierdurch the fluoroelastomer composition is present as a polymer blend, that is

Polyamide is present in the fluoroelastomer molecularly or microscopically dispersed. In practical experiments, it has been found that such fluoroelastomer compositions cure well even in the absence of metal oxides, so that they have a low swelling tendency and good swelling tendency

Flitze resistance can be achieved. A disadvantage of this

However, compositions are that they show an unsatisfactory compression set.

The object of the present invention is to provide a

To provide fluoroelastomer composition, which in addition to a low swelling tendency and good Flitzebeständigkeit also a good

Compression set shows.

This problem is solved by a hardenable

Fluoroelastomer composition comprising:

A) a, preferably free-radically, curable fluoroelastomer; B) a curing system; and

C) from 0.1% to 30% by weight of a nitrogen-containing polymer,

selected from polyamide, polyimide, mixtures and / or copolymers thereof, each based on the total weight of fluoroelastomer and nitrogen-containing polymer, wherein the nitrogen-containing polymer in particulate form having an average particle size in the range of 0.15 to 70 pm and / or in fiber form with a middle one

Fiber diameter in the range of 0.15 to 70 pm is present.

It has been found that the inventive

Fluoroelastomer composition containing as additive the nitrogen-containing polymer in particulate form having an average particle size in the range of 0.15 to 70 pm and / or in fiber form with an average fiber diameter in the range of 0.15 to 70 pm, surprisingly both a low swelling tendency and good Flitzebeständigkeit as well as a good compression set, in the form of a significantly improved tensile strength even after flash aging, for example at 250 ° C shows.

According to the invention, the fluoroelastomer composition comprises nitrogen-containing polymer selected from polyamide, polyimide, mixtures and / or copolymers thereof, in each case in particle form having an average particle size in the range of 0.15 to 70 μm and / or in fiber form with a mean fiber diameter in the range of 0 , 15 to 70 pm. The nitrogen-containing polymer, if present in particle form, preferably has an average particle size in the range from 0.2 to 50 μm, more preferably in the range from 0.3 to 30 μm, even more preferably in the range from 0.4 to 20 μm, even more preferably in the range from 0.4 to 12.5 μm, in particular in the range from 0.4 to 8 μm, and / or, if it is in fiber form, an average fiber diameter in the range from 0.2 to 50 μm, more preferably in the range of 0.3 to 30 pm, more preferably in the range of 0.4 to 20 pm, still more preferably in the range from 0.4 to 12.5 miti, in particular in the range from 0.4 to 8 miti.

According to the invention, the mean particle size is determined according to ISO 13320 and the mean fiber diameter after image analysis.

In a preferred embodiment of the invention, the

Fluoroelastomer composition accounted for as an acid acceptor

functioning metal oxide, in particular zinc oxide, magnesium oxide,

Calcium oxide and / or to lead oxide (Pb0 / Pb304) of less than 1, 5 wt.% And / or a proportion of acting as an acid acceptor metal hydroxide, in particular calcium hydroxide, of less than 1, 5 wt.% And / or a proportion of as an acid acceptor functioning metal salt, in particular hydrotalcite, calcium and / or magnesium stearate of less than 5 wt.%, Wherein the quantities are in each case based on the total weight of

Fluoroelastomer composition.

According to the invention, the fluoroelastomer composition contains a curable fluoroelastomer. The proportion of fluoroelastomer in the fluoroelastomer composition is preferably from 40% by weight to 95% by weight, in particular from 50% by weight to 90% by weight, based in each case on the total weight of the

Fluoroelastomer composition.

Various types of fluoroelastomers are suitable for use as a curable elastomer. Suitable fluoroelastomers include, in particular, those classified as FKM, FFKM and FTPM in ASTM-D 1418, "Standard Practice for Rubber and Rubber Grid Nomenclature".

The term FKM is used for fluoroelastomers that use vinylidene fluoride as a comonomer. Various types of fluoroelastomers are available in the Trade available. A first grade may be described chemically as a copolymer of hexafluoropropylene and vinylidene fluoride. These

Fluoroelastomers tend to be an advantageous combination of

To have overall properties. Some commercial embodiments are available with about 66 wt% fluorine. Another type of FKM can be chemically described as a terpolymer of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride. Such elastomers tend to have high heat resistance and good resistance to aromatic solvents. They are commercially available with, for example, 68-69.5 wt.% Fluorine. Another FKM is chemically termed a terpolymer

Tetrafluoroethylene, a fluorinated vinyl ether and vinylidene fluoride described. Such elastomers tend to have improved low temperature performance. In various embodiments, they are available with 62-68 wt.% Fluorine.

Another type of fluoroelastomer is described as a terpolymer of tetrafluoroethylene, propylene and vinylidene fluoride. Such fluoroelastomers tend to have improved base resistance. Some commercial

Embodiments contain about 67% by weight fluorine. Another type of fluoro-elastomer may be used as a pentapolymer of tetrafluoroethylene,

Hexafluoropropylene, ethylene and a fluorinated vinyl ether and

Vinylidene fluoride are described. Such elastomers typically have improved base stability and improved low temperature performance.

Another category of fluoroelastomers is referred to as FFKM. These elastomers may be referred to as perfluoroelastomers because the

Polymers are fully fluorinated and contain no carbon-hydrogen bond. FFKM fluoroelastomers are generally characterized by excellent fluid resistance. They were originally from DuPont introduced under the trademark Kalrez ^®. Other suppliers are Daikin and Ausimont.

Another category of fluoroelastomers is referred to as FTPM.

Typical of this category are the copolymers of propylene and

Tetrafluoroethylene. The category is characterized by a high resistance to basic materials such as amines.

Suitable fluoroelastomers include commercially available copolymers of one or more fluorochemical monomers, mainly vinylidene fluoride (VDF), hexafluoropropylene (HFP), tetrafluoroethylene (TFE) and perfluorovinyl ether (PFVE). Preferred PFVE include those having a C 1 -8

Perfluoroalkyl group, preferably perfluoroalkyl groups having 1 to 6

Carbon atoms and in particular perfluoromethylvinylether and

Perfluorpropylvinylether.

In addition, the copolymers may also contain repeating units derived from olefins such as ethylene (Et) and propylene (Pr).

In various preferred embodiments, the fluoroelastomer is a so-called base-stable fluoroelastomer. Such base-stable fluoroelastomers also include fluoroolefin copolymers. Particularly preferred is a copolymer of tetrafluoroethylene with at least one C2-4 olefin and so-called cure site monomers (CSM).

Optionally, the fluoroelastomer contains repeating units derived from one or more additional fluorochemical monomers. As such, the cured elastomeric material comprises

Repeating units derived from tetrafluoroethylene and at least one C2-4 olefin, and further includes peroxide crosslinking sites. In a preferred embodiment, the fluoroelastomer comprises repeating units derived from 10-90 mole percent tetrafluoroethylene, 10-90 mole percent C2-4 olefin, and up to 30 mole percent of one or more additional fluorine-containing monomers. Preferably, the

Repeated units of 25-90 mol.% Of tetrafluoroethylene and 10-75 mol.% C2-4 Olefin derived. In another preferred embodiment, the repeating units are derived from 45-65 mole percent tetrafluoroethylene and 20-55 mole percent C2-4 olefin.

In a particularly preferred embodiment, the molar ratio of tetrafluoroethylene units to C2-4 olefin repeat units is from 60:40 to 40:60. In various embodiments, the fluoroelastomer comprises alternating units of C 2-4 olefins and tetrafluoroethylene. In such polymers, the molar ratio of tetrafluoroethylene to C2-4 olefin is about 50:50.

In another embodiment, the fluoroelastomers are described as

Block copolymers provided with an A-B-A structure, wherein A represents a block of polytetrafluoroethylene and B represents a block of polyolefin.

A preferred C2-4 olefin is propylene. Fluoroelastomers based on copolymers of tetrafluoroethylene and propylene are available at Flandel, for example from Asahi under the Flandelsnamen Aflas ^®.

A preferred additional monomer in the fluoroelastomer is

Vinylidene. Other fluorine-containing monomers used in the

fluoroelastomers of the invention can be used, including, without limitation, perfluoroalkylvinyl compounds,

Perfluoroalkylvinylidene compounds and perfluoroalkoxyvinyl compounds. Hexafluoropropylene (HFP) is an example of a perfluoroalkylvinyl monomer. Perfluoromethyl vinyl ether is an example of a preferred one

Perfluoralkoxyvinylmonomer. For example, rubbers are available on the basis of copolymers of tetrafluoroethylene, ethylene and perfluoromethyl by DuPont under the trade name Viton ^® ETP commercially.

Fluoroelastomers used in the preparation of processable

Rubber compositions of the invention may be used typically by free-radical emulsion polymerization of a

Monomer mixture are prepared containing the desired molar ratios of the starting monomers. Initiators are typically organic or inorganic peroxide compounds, and that is emulsifier

typically a fluorinated acid soap. The molecular weight of the polymer formed can be controlled by the relative amounts of initiators used as compared to the monomer content and the choice of transfer agent, if any. Typical transfer agents include

Carbon tetrachloride, methanol and acetone. The emulsion polymerization may be carried out under batch or continuous conditions. Such fluoroelastomers are commercially available as above

specified.

The fluoroelastomers used in the compositions and methods of the invention, as described above, preferably contain repeating units derived from one or more fluorochemical olefinic monomers.

The fluoroelastomers are curable according to the invention. The fluoroelastomers are preferably free-radically and / or ionically curable. Among free-radically curable fluoroelastomers, fluoroelastomers are too

understand that contain so-called crosslinks.

In a preferred embodiment, the free-radically curable fluoroelastomers contain as crosslinking sites repeating units based on so-called cure site monomers (CSM), which are described in more detail below. The repeating units are based on the corresponding monomers in the sense that the structure of the polymer results from copolymerization of the monomers and the resulting structure is the addition polymerization product of the monomers. In the cured fluoroelastomers, at least some of the recurring units derived from the cure site monomers are crosslinked. In one embodiment, crosslinking is by the reaction of multifunctional

Crosslinking coagents formed with radicals at the crosslinking sites, which is induced for example by the action of an organic peroxide of the radical free radical system.

In various embodiments, the radically curable fluoroelastomers contain up to 5 mole%, for example, from 0.05 to 5 mole%.

Repeating units based on the so-called cure site monomers. In one embodiment, the crosslink sites are based on halogen-containing olefin monomers wherein the flalogen is chlorine, bromine, iodine, or combinations of these. If used, the

Repeating units of a halogen-containing olefin are preferably present in an amount of at least about 0.05% by weight of flalogen in the

Fluoroelastomer, preferably 0.3% by weight of flalogen or more,

provide. In a preferred embodiment this is

Total weight of flalogen in the fluoroelastomer 1.5% by weight or less. The cure site monomers generate crosslinks in the fluoroelastomer, preferably with radical initiators, such as high-peroxide peroxides

Speed respond. They react faster than other parts of the world

Elastomers. The crosslinking is thus preferably carried out at the crosslinking sites. This crosslinking effect is at least partially responsible for the elastomeric properties in the elastomer. Non-limiting examples of cure site monomers include brominated, chlorinated and iodinated olefins;

brominated, chlorinated and iodinated unsaturated ethers; and non-conjugated dienes.

In preferred embodiments, the free-radically curable

Fluoroelastomers peroxide-curable fluoroelastomers, preferably

at least one halogenated crosslinking site or a reactive one

Double bond resulting from the presence of a copolymerized unit of a non-conjugated diene include. The double bond of the cure site monomer is referred to herein as an olefin. Functional groups associated with the cure sites thus include a carbon-bromine (C-Br) bond, a carbon iodide (C-1) bond, a carbon-chlorine (C-Cl) bond, and an olefin. In various embodiments, halogenated cure sites are provided by copolymerized cure site monomers and / or by flurogen atoms present at the terminal positions of the fluoroelastomer polymer chain. In general, the halogenated crosslinks are referred to as repeating units derived from a cure site monomer. Copolymerized cure site monomers, reactive double bonds and halogenated end groups are capable of reacting to form crosslinks, particularly under catalysis or initiation by the action of peroxides.

As can be seen from this discussion, repeat units of an uncured fluoroelastomer based on cure site monomers contain one or more of these functional groups. In cured elastomers, at least some of the functional groups are reacted with the cure system. In both cases, the elastomer contains repeating ones

Units derived from cure site monomers.

Brominated cure site monomers may contain other halogens, preferably fluorine. Examples are bromotrifluoroethylene, 4-bromo-3,3,4,4-tetrafluorobut-1-ene and others such as vinyl bromide, 1-bromo-2,2-difluoroethylene, perfluoroallyl bromide, 4-bromo-1,1,2-trifluorobutene, 4-bromo-1,1,3,3,4,4-hexafluorobutene, 4-bromo-3-chloro

1.1.3.4.4-pentafluorobutene, 6-bromo-6-tetrafluorohexene, 4-bromoperfluorobut-1-ene and 3,3-difluoroallyl bromide. Brominated unsaturated ether-cure site monomers useful in the invention include ethers such as

Bromoperfluoroethyl perfluorovinyl ethers and fluorinated compounds of class CF2 Br-Rf-O-CF-CF2 (Rf is perfluoroalkylene) such as CF2 BrCF2 O-CF-CF2 and fluorovinylethers of class ROCF-CFBr or ROCBr-CF2 wherein R is a lower alkyl group or fluoroalkyl group such as CH30CF-CFBr or

CF3CH20CF-CFBr. Flamed olefins can also be used as cure site monomers. Suitable iodinated monomers include iodinated olefins of the formula: CHR-CH-Z-CH 2 CHR-I, wherein R is -H or

-CH3 is; Z is a C 1 -C 18 (per) fluoroalkylene radical, linear or branched, which optionally contains one or more ether oxygen atoms, or a

(Per) fluoropolyoxyalkylene radical as described in US Pat. 5,674,959. Other examples of suitable iodinated cure site monomers are unsaturated ethers of the formula I (CH 2 CF 2 CF 2) n OCF-CF 2 and ICH 2 CF 2 O [CF (CF 3) CF 2 O] n CF-CF 2 and the like as described in U.S. Pat. No. 5,717,036. In addition, suitable iodinated cure site monomers may be used including iodoethylene, 4-iodo

3.3.4.4-tetrafluorobutene-1; 3-chloro-4-iodo-3,4,4-trifluorobutene; 2-iodo-1,1,2,2-tetrafluoro-1 - (vinyloxy) ethane; 2-iodo-1 - (perfluorovinyloxy) -l, 1, 2,2- tetrafluoroethylene; 1,1,3,3,3-hexafluoro-2-iodo-1 - (perfluorovinyloxy) propane; 2-iodoethyl vinyl ether; 3,3,4,5,5,5-hexafluoro-4-lodopenten; and iodotrifluoroethylene as described in U.S. Pat. No. 4,694,045. Examples of non-conjugated diene-cure site monomers include 1, 4-

Pentadiene, 1,5-hexadiene, 1,7-octadiene and others such as those disclosed in Canadian Patent 2,067,891. A suitable triene is 8-methyl-4-ethylidene-1, 7-octadiene. Of the above listed cure site monomers, preferred ones include

Compounds 4-bromo-3,3,4,4-tetrafluorobut-1-ene; 4-iodo-3,3,4,4-tetrafluorobut-1-ene; and bromotrifluoroethylene. Additionally or alternatively, cure site monomers and repeating units derived therefrom and containing iodine, bromine, or mixtures thereof are transmitted at the ends of the fluoroelastomer chains as a result of the use of chains

Molecular weight regulators during the preparation of

Fluoroelastomers present. Such agents include iodine-containing

Compounds which yield iodine bound at one or both ends of the polymer molecules. Methylene iodide; 1,4-diiodoperfluoro-n-butane; and 1,6-diiodo-3,3,4,4-tetrafluorohexane are representative of such agents. Other iodinated chain transfer agents include 1, 3-diiodoperfluoropropane; 1,4-diiodoperfluorobutane; 1, 6-diiodoperfluorohexane; 1, 3-diiodo-2-chloroperfluoropropane;

1,2-di (iododifluoromethyl) perfluorocyclobutane; Monoiodperfluorethan;

monoiodoperfluorobutane; and 2-iodo-1-hydroperfluoroethane. Particularly preferred are diiodinated chain transfer agents. Examples of brominated

Chain transfer agents include 1-bromo-2-iodoperfluoroethane; 1 -bromo-3-iodoperfluoropropane; 1-iodo-2-bromo-1, 1-difluoroethane and others as disclosed in U.S. Pat. No. 5,151, 492. Non-limiting examples of peroxide curable fluoroelastomers include VDF / HFP / CSM, VDF / HFP / TFE / CSM, VDF / PFVE / TFE / CSM, TFE / Pr / CSM, TFE / Pr / VDF / CSM, PFVE / VDF / CSM, TFE / Et / PFVE / CSM and TPE / PFVE / CSM, where CSM is at least one cure site monomer. The name of the elastomer indicates the monomers from which the

Elastomeric rubbers are synthesized. In some embodiments, the elastomeric rubbers have viscosities that have a Mooney viscosity in the

general of 15-160 (ML1 + 10, large rotor at 121 ° C).

Elastomer suppliers include Dyneon (3M), Asahi glass fluoropolymers,

Solvay / Ausimont, DuPont and Daikin.

The radical-curing system (B) preferably contains a

Radical initiator and a crosslinking coagenz. It is believed that the free radical initiator works by first extracting a hydrogen or flalogen atom from the fluoroelastomer to generate a free radical that can be crosslinked. It is believed that the above-described cure site monomers provide sites that react with the free radical initiator at an accelerated rate such that the following, below

crosslinking occurs mainly at the crosslinking sites. These crosslinks contain the free radicals associated with the

unsaturated sites of the crosslinking coagents can react.

Crosslinking coagents contain at least two unsaturated, preferably olefinically unsaturated, sites.

In various embodiments, the free radical initiators have a

Peroxide functionality. As examples of radical initiators, numerous organic peroxides are known and available in the Flandel. The radical initiators, including the organic peroxides, are over a wide

Temperature range can be activated. The activation temperature can be below

Using a parameter known as Flalbwertszeit (T1 / 2) described become. Typical values for half-lives of, for example, 0.1 hours, 1 hour and 10 hours are given in degrees Celsius. For example, a T1 / 2 at 143 ° C for 0.1 hour indicates that at this temperature half of the free radical initiator decomposes within 0.1 hour. Organic peroxides with a T1 / 2 at 0.1 hours from 118 ° C to 228 ° C are commercially available. Such peroxides have a half-life of at least 0.1 hours at the indicated temperatures. The T1 / 2 values indicate the kinetics of the initial reaction in the crosslinking of the fluoroelastomers, ie, the decomposition of the peroxide to form a radical-containing intermediate.

Non-limiting examples of commercially available organic peroxides for initiating curing of fluoroelastomers include butyl 4,4-di (tert-butylperoxy) valerate; tert-butyl peroxybenzoate; Di-tert-amyl peroxide;

dicumyl peroxide; Di (tert-butylperoxyisopropyl) benzene; 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane; tert-butyl cumyl peroxide; 2,5-dimethyl-2,5-di (tert-butylperoxy) hex-3-yn; Di-tert-butyl peroxide; 3,6,9-triethyl-3,6,9-trimethyl-1, 4,7-triperoxonane; 1,1,3,3-tetramethylbutyl hydroperoxide;

diisopropylbenzene; cumyl; tert-butyl hydroperoxide; tert-amyl hydroperoxide; tert-butyl peroxyisobutyrate; tert-amyl peroxyacetate; tert-Butylperoxystearylcarbonat; Di (1-hydroxycyclohexyl) peroxide; Ethyl-3,3-di (tert-butylperoxy) butyrate; and tert-butyl 3-isopropenyl cumyl peroxide.

Non-limiting examples of crosslinking coagents include

triallyl; triallyl; Tri (methallyl) -isocyanurate; Tris (diallylamine) -s-triazine, triallyl phosphite; N, N-diallylacrylamide; hexaallyl phosphoramide; N, N, N ', N'-tetraallyl terephthalamide; N, N, N ', N'-tetraallylmalonamide;

trivinyl; 2,4,6-trivinyl methyltrisiloxane; and tri (5-norbornene-2-methylene) cyanurate. The crosslinking coagents preferably contain at least two sites of olefinic unsaturation. The unsaturated ones Sites react with the free radical generated on the fluoroelastomer molecule and crosslink the elastomer. A commonly used crosslinking agent is triallyl isocyanurate (TAIC).

By ionic curable fluoroelastomers are to be understood, which can be cured with amines, preferably diamines and / or polyols, preferably bisphenols. Ionically curable fluoroelastomers are well known and described in the literature, for example, in Albert L. Moore, Fluorelastomers Handbook: The Definitive User ^'s Guide and Databook.

In addition to the fluoroelastomer, cure system, and nitrogen-containing polymer, the fluoroelastomer composition of this invention may contain other additives such as stabilizers, processing aids,

Hardening accelerators, fillers, pigments, dyes, adhesives,

Tackifiers and waxes are added.

A wide variety of processing aids can be used, including plasticizers and mold release agents. Non-limiting examples of processing aids include carnauba wax, ester plasticizers such as dioctyl sebacate (DOS), fatty acid salts such as zinc stearate and sodium stearate, polyethylene wax and ceramide. In some embodiments, high temperature processing aids are preferred. Such include, without limitation, linear fatty alcohols such as mixtures of C10-C28 alcohols, organo-silicones, and functionalized perfluoropolyethers. In some embodiments, the compositions contain from about 0.5 to about 15 weight percent processing aid, preferably from about 0.5 to about 10 weight percent.

As explained above, the inventive

Fluoroelastomer composition, preferably no to small amounts of the usually preferred acid acceptor compounds comprising oxides and hydroxides of divalent metals. Non-limiting examples include Ca (OH) 2, MgO, CaO and ZnO. Preferably, the

Compositions of the invention substantially free of acid acceptors, in particular the aforementioned acid acceptors, by "substantially free" being less than 0.1 (preferably 0) parts by weight per 100 parts by weight of fluoroelastomer.

Non-limiting examples of fillers include both organic and inorganic fillers such as barium sulfate, carbon black, graphite, plastic powders such as PTFE powder, silica, titania, glass fiber,

Fumed silica, graphene and fibers such as mineral fibers, plastic fibers such as ultrahigh molecular weight polyethylene fibers,

Carbon fibers, carbon nanotubes (CNTs), boron fibers. In various embodiments, fillers such as plastic powders such as PTFE powder, graphite, and CNT are used to improve the wear resistance and other properties of molded parts intended for use, for example, as dynamic seal members.

In a preferred embodiment, fillers such as carbon black may constitute up to about 70% by weight of the total weight of the compositions of the invention. Preferably, the compositions comprise 1 to 50

Wt.% Filler. In other embodiments, the filler constitutes 10 to 30% by weight of the compositions.

The fluoroelastomer, cure system, nitrogen-containing polymer, and any other ingredients may be incorporated into a curable fluoroelastomer composition using, for example, an internal mixer or mill at a temperature below the melting temperature of the nitrogen-containing polymer, using conventional procedures in the rubber industry. Other ingredients that can be added include those commonly used as described above

Fluoroelastomer compositions can be used.

The resulting curable composition can then be molded (e.g., molded or extruded) and cured to form a fluoroelastomer article. Curing typically takes place at about 150 to 200 ° C for 1 to 60 minutes.

Conventional suitable rubber curing presses, molds, extruders and the like can be used. For optimal physical

Properties and dimensional stability, it is also preferable to a

To perform a post-curing operation in which the molded or extruded fluoroelastomer article in an oven or the like for a

additional period of about 1 to 48 hours, typically heated from about 180 to 275 ° C.

The nitrogen contained in the fluoroelastomer composition

containing polymers are inventively selected from polyamide, polyimide, mixtures and / or copolymers thereof. These polymers may be amorphous, semi-crystalline or crystalline, linear, branched, crosslinked or uncrosslinked.

In the present invention, the content of nitrogen-containing polymer in the fluoroelastomer composition is 0.1 wt% to 30 wt%, preferably 0.1 wt% to 15 wt%, more preferably 0.1 wt% to 10 wt%. %, more preferably from 0.1% to 5% by weight, based in each case on the total weight of fluoroelastomer and nitrogen-containing polymer.

Particularly suitable nitrogen-containing polymers are those having a melting temperature determined in accordance with ASTM D3418-08, or

Decomposition temperature of more than 180 ° C, for example from 180 ° C to 1000 ° C, preferably more than 190 ° C, for example from 190 ° C to 1000 ° C, more preferably more than 200 ° C, for example from 200 ° C to 1000 ° C, most preferably more than 215 ° C, for example from 215 ° C to 1000 ° C. Preferably, the nitrogen-containing polymer is in the

Curing temperature of the fluoroelastomer, which means that the

Curing temperature of the fluoroelastomer is lower than that

Melting temperature, the glass transition temperature or

Decomposition temperature of the polymer, whichever is greater.

Polyamides useful in the practice of the invention include:

aliphatic polyamides, such as nylon 6, nylon 7, nylon 6/6, nylon 6/10, nylon 6/12, nylon 11, nylon 12, aromatic and partially aromatic polyamides, such as p-aramid, m-aramid, polyphthalamides, and aliphatic, aromatic and / or partially aromatic polyamide copolymers, such as copoly (amide ether),

Copoly (amide esters).

In certain embodiments, a polyamide having an amine end group content greater than 30 meq / kg may be desirable.

Examples of polyamides include polyhexamethylene adipamide (6,6 nylon), polyhexamethylene azelamide (6,9 nylon), polyhexamethylene sebacamide (6,10 nylon) and polyhexamethylene dodecanoamide (6,12 nylon) wherein the polyamide is prepared by ring opening of lactams, ie polycaprolactam, polylauriclactam , Poly-11-aminoundecanoic acid and bis (p-aminocyclohexyl) methandodecanoamide. It is also possible to use polyamides prepared by copolymerizing two of the above polymers or terpolymerizing the above polymers or their components, such as adipic acid-isophthalic acid-hexamethylenediamine copolymer. Typically, polyamides are condensation products of one or more dicarboxylic acids and one or more diamines and / or a or more aminocarboxylic acids and / or ring-opening

Polymerization products of one or more cyclic lactams.

Aliphatic polyamides useful in the practice of the present invention may be selected from aliphatic and alicyclic monomers such as diamines, dicarboxylic acids, lactams, aminocarboxylic acids and their reactive ones

Equivalents are formed. A suitable aminocarboxylic acid is 1,1-aminododecanoic acid. Suitable lactams are caprolactam and laurolactam. Linear, branched and cyclic monomers can be used.

Carboxylic acid monomers that can be used to prepare aliphatic polyamides include aliphatic carboxylic acids, such as adipic acid, pimelic acid, suberic acid, azelaic acid, decanedioic acid,

Dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid and pentadecanedioic acid. Diamines can be made from diamines with four or more carbon atoms

be selected, including, but not limited to

Tetramethylenediamine, hexamethylenediamine, octamethylenediamine,

Decamethylenediamine, dodecamethylenediamine, 2-methylpentamethylenediamine, 2-ethyltetramethylenediamine, 2-methyloctamethylenediamine;

Trimethylhexamethylenediamine, meta-xylylenediamine and / or mixtures thereof.

Aromatic and partially aromatic polyamides are homopolymers, dipolymers, terpolymers or higher order polymers formed from monomers containing aromatic groups. One or more aromatic carboxylic acids may be terephthalic acid or a mixture of

Terephthalic acid with one or more other carboxylic acids, such as

Isophthalic acid, phthalic acid, 2-methyl terephthalic acid and naphthalic acid. In addition, the one or more aromatic carboxylic acids may be mixed with one or more aliphatic dicarboxylic acids. alternative For example, an aromatic diamine such as meta-xylylenediamine can be used to provide a partially aromatic polyamide.

Block copoly (amide) copolymers are also suitable as polyamide component. When the block copoly (amide) copolymer, e.g. For example, a polyether oligomer or a polyalkylene ether, such as poly (ethylene oxide) comprises, then the block copolymer is a copoly (amide ether). If the block copoly (amide) copolymer comprises an ester, for example a polylactone such as polycaprolactone, then the block copolymer is a copoly (amide ester). Preferably, the block copoly (amide) copolymer is a block copoly (amide ester)

Block copoly (amide ether) or a mixture thereof.

Preferred polyamides are homopolymers or copolymers wherein the term copolymer refers to polyamides having two or more amide and / or diamide repeating units. The

Polyamide component may be one or more aliphatic or

semiaromatic polyamides include, for example

Poly (pentamethylenedecanediamide), poly (pentamethylenedodecanediamide), poly (e-caprolactam / hexamethylenehexanediamide), poly (e-caprolactam /

Hexamethylene decanediamide), poly (12-aminododecanamide), poly (12-aminododecanamide / tetramethylene terephthalamide) dodecanediamide);

Poly (tetramethylenehexanediamide), poly (e-caprolactam),

Poly (hexamethylenehexanediamide), poly ((hexamethylene) dodecanediamide) and poly (hexamethylenetetradecandiamide); Polyamides having semiaromatic repeating units derived from monomers selected from one or more of the group consisting of aliphatic and / or aromatic dicarboxylic acids having 8 to 20 carbon atoms and aliphatic diamines having 4 to 20 carbon atoms.

The polyamide may also be a mixture of two or more polyamides. Preferred polyamides have a melting temperature which is sufficiently high so as not to affect the range of application for the curable fluoroelastomer compositions.

Also preferred are polyamides formed by ring opening or condensation of aminocarboxylic acids.

Polyamides which are suitable for use in the invention are widely available commercially, such as Zytel ^®, Kevlar ^® available from EI du Pont de Nemours and Company, Wilmington, Delaware, USA, Durethan ^®, available from Lanxess, Germany, and Ultramid ^® resins, available from BASF, USA, Twaron ^®, available from TEIJIN, Netherlands.

Polyimides according to the invention include polymers whose most important structural feature is the imide group. Polyimides which contain further structural elements such as ester groups, amide groups, etc., such as polyetherimides (PEI), polyamide-imides (PAI) are also to be understood according to the invention as polyimides.

Particularly preferred polyimides or polyamide-imides can be obtained by polycondensation of at least one aromatic

Tetracarboxylic acid (di) anhydride or an aromatic tricarboxylic acid, preferably selected from the group consisting of 3, 4, 3 ', 4'-benzophenone tetracarboxylic dianhydride, 1, 2,4,5-benzene tetracarboxylic acid dianhydride, 3,4,3' 4'-biphenyl,

Oxydiphthalic acid dianhydride, sulfonyldiphthalic dianhydride, and 1,1,1,3,3,3-hexafluoro-2,2-propylidenediphthalic dianhydride, 1,4-benzenetricarboxylic acid and at least one aromatic diisocyanate, preferably selected from the group consisting of toluene 2,4-diisocyanate, toluene-2,6-diisocyanate, 4,4'-methylenediphenyl-diisocyanate, 2,4,6-trimethyl-1,3-phenylenedi-isocyanate, 2.3.4.5-tetramethyl-1, 4-phenylene diisocyanate or by reaction

at least one tetracarboxylic acid (di) anhydride, preferably selected from the group consisting of 3,4,3 ', 4'-benzophenone tetracarboxylic dianhydride,

1,2,4,5-benzenetetracarboxylic dianhydride, 3,4,3'4'-biphenyltetracarboxylic dianhydride, oxydiphthalic dianhydride, sulfonyldiphthalic dianhydride, and 1,1,3,3,3-hexafluoro-2,2-propylidenediphthalic dianhydride, 4, 4'- (4,4'-isopropylidenediphenoxy) bis (phthalic anhydride); and at least one diamine, preferably selected from the group consisting of 2,4-diaminotoluene, 2,6-diaminotoluene, 4,4'-diaminodiphenylmethane, 2,4,6-trimethyl-1,3-phenylenediamine, 2,3, 4,5-tetramethyl-1,4-phenylenediamine, bis (4-amino-3,5-dimethyl-phenyl) -methane, bis (4-amino-3-methyl-phenyl) -methane, 1, 3-phenylenediamine, 1, 4-phenylenediamine, 4,4'-diaminodiphenyl ether, 5 (6) -amino-1 - (4'-aminophenyl) -1,3'-trimethylindane, followed by imidization of the polyamic acid.

Very particularly preferred polyimides include



wherein 0 <x <0.5 and 1> y> 0.5 and R corresponds to one or more identical or different radicals selected from the group consisting of L1, L2, L3 and L4.

X = 0, y = 1 and R consists of 64 mol% of L2, 16 mol% of L3 and 20 mol% of L4. This polymer is commercially available under the name P84 or P84 type 70 from Evonik Fibers and is registered under CAS number: 9046-51 -9. In another particularly preferred polymer, x = 0.4, y = 0.6, and R is 80 mole% of L2 and 20 mole% of L3. This polymer is commercially available as P84HT from Evonik Fibers and is registered under the CAS number: 134119-41 -8. Also suitable are the polyamide polymers with brand name Torlon ^® KERMEL ^® and with the subsequent services mentioned above composition,

wherein the radical R corresponds to one or more, identical or different radicals selected from the group consisting of L2, L3 and L4.

Polyimides which are suitable for use in the invention are widely available commercially, for example, polyimide P84 ^® NT polyimides available from Evonik, Germany, Kapton ^®, Vespel ^® available from EI du Pont de Nemours and Company, Wilmington, Delaware, USA, and Torlon ^®, available from Solvay, Belgium.

In a preferred embodiment of the invention, the

Fluoroelastomer composition in the cured state

Volume swelling in 20% acetic acid after 168 h / 95 ° C, measured according to DIN ISO 1817, from 0 to 25 percent by volume, more preferably from 0 to 15 percent by volume, in particular from 0 to 10 percent by volume. In a preferred embodiment of the invention, the fluoroelastomer composition in the cured state has one

Compression set after 168 h / 200 ° C, measured according to DIN ISO 815, from 0 to 70 percent, for example 1 to 70 percent, on, more preferably from 0 to 60 percent, for example 1 to 60 percent, to, in particular from 0 to 40 percent , for example 1 to 40 percent.

The invention further relates to a process for the preparation of a curable fluoroelastomer composition according to one or more of

Embodiments described according to the invention comprising the steps:

A) providing a curable, preferably free-radically curable,

in particular peroxide-curable fluoroelastomers;

B) providing a nitrogen-containing polymer selected from

Polyamide, polyimide, mixtures and / or copolymers thereof, wherein the nitrogen-containing polymer is in particle form having an average particle size in the range of 0.1 to 70 pm and / or in fiber form with a mean fiber diameter in the range of 0.1 to 70 pm ;

C) mixing the curable fluoroelastomer with the nitrogen-containing polymer at a temperature which is less than the melting temperature or decomposition temperature of the nitrogen-containing polymer, whichever is lower to form a polymer blend, the curable fluoroelastomer and 0.1 wt % to 30% by weight

Nitrogen-containing polymer, based on the total weight of fluoroelastomer and nitrogen-containing polymer, and

D) adding a curing system, in particular a peroxide curing agent and a crosslinking coagent, to the Polymer mixture at a temperature lower than that

Melting temperature or decomposition temperature of the nitrogen-containing polymer, whichever is lower, to form a curable fluoroelastomer composition.

The fluoroelastomer composition according to the invention is outstandingly suitable for the production of seals, in particular O-rings, frame seals, radial shaft seals, bellows and

Valve stem seals.

Another object of the present invention is a seal comprising a fluoroelastomer according to one or more of the embodiments described herein and their use in acidic media.

In the following the invention will be explained in more detail with reference to several examples. Materials used:

FKM 1: peroxide-crosslinkable copolymer of vinylidene fluoride,

Tetrafluoroethylene and flexafluoropropylene, fluorine content 67%, Mooney viscosity 21 (ML1 +10 @ 121 ° C)

FKM 2: peroxide crosslinkable copolymer of vinylidene fluoride and

Flexafluoropropylene, fluorine content 66%, Mooney Viscosity 30 (ML1 +10 @ 121 ° C)

Carbon Black: soot, thermal carbon black N-990

Peroxide: dicumyl peroxide Crosslinking coagulation: triallyl isocyanurate

Polyamide 6: Polyamide 6 powder, particle size 20 miti

Polyamide 6,6: Polyamide fiber, fiber diameter 27 - 30 miti

Polyaramid 1: polyaramid fiber pulp, 40% p-aramid, poly (p-phenylene terephthalamide), fiber diameter <70 μm

Polyaramid 2: polyaramid powder, p-aramid, poly (p-phenylene terephthalamide),

Particle size> 70 pm

Polyimide 1: polyimide, POLYIMIDE P84 ^® NT1, particle size 1 - 10 pm

Polyimide 2: polyimide, polyimide P84 ^® NT2, particle size 1 - 10 pm

1) Preparation of various peroxide-curable fluoroelastomer compositions

From the aforementioned materials, various peroxide-curable fluoroelastomer compositions were prepared in 2 stages with an internal mixer and a rolling mill suitable for the preparation of rubber compounds. The tests were carried out on test plates, which were vulcanized for 5 min at 180 ° C and reheated for 24 h at 200 ° C.

The following fluoroelastomer compositions were prepared and tested for various parameters relevant for sealing applications. CE1

Comparison mixture: Metal oxide-free FKM mixture. The cross-linked material shows a significant drop in tensile strength after air aging for 168 h at 250 ° C compared to CE2.

CE2

Comparison mixture: Metal oxide FKM mixture containing 1.5 phr ZnO.

The crosslinked material shows a high swelling after storage in acetic acid. EA1

Polyamide 6-containing mixture: metal oxide-free FKM mixture with 3 phr polyamide 6.

The tensile strength after air aging is comparable to CE2. EA2

Polyamide fiber-containing blend: metal oxide-free FKM blend with 3 phr polyamide 6.6 fiber.

The tensile strength after air aging is comparable to CE2. The swelling in acetic acid shows an improvement over CE1.

EA3

Polyaramid fiber containing blend: metal oxide free FKM blend with 5 phr polyaramid fiber. The measured compression set are comparable to CE1 and CE2.

The swelling in acetic acid shows an improvement over CE1.

EA4

Polyaramid-containing mixture: metal oxide-free FKM mixture with 6 phr

Polyaramid powder. The measured compression set are comparable to CE1 and CE2.

The swelling in acetic acid shows an improvement over CE1.

EU

Polyimide-containing blend: metal oxide-free FKM blend with 6 phr polyimide 1 powder.

The tensile strength after air aging 168 h at 250 ° C is comparable to CE2, the measured compression set are comparable to CE1 and CE2.

The swelling in acetic acid shows an improvement over CE1.

EI2

Polyimide-containing blend: metal oxide-free FKM blend with 6 phr polyimide 2 powder.

The swelling in acetic acid shows an improvement over CE1.

EI3

Polyimide-containing blend: metal oxide-free FKM blend with another FKM base polymer and with 6 phr polyimide 2 powder. The tensile strength after air aging 168 h at 250 ° C is comparable to CE2, the measured

Compression set is comparable to CE1 and CE2. The swelling in acetic acid shows an improvement over CE1. EI4

Polyimide-containing blend: metal oxide-free FKM blend with another FKM base polymer and with 30 phr polyimide 1 powder. The measured compression set are comparable to CE1 and CE2.

EI5

Polyimide-containing blend: metal oxide-free FKM blend with another FKM base polymer and with 30 phr polyimide 2 powder. The swelling in

Acetic acid shows an improvement over CE1.

2) Results of the tests

The results of the tests are shown in the table below.

It can be seen that the polyimide-containing mixtures EU, EI2 and EI3 show the best properties for air aging and swelling in acetic acid, as well as no significant deterioration of Druckverfomungsrestes against CE1 and CE2.

Claims

claims

A curable fluoroelastomer composition comprising:

A) a curable fluoroelastomer;

B) a curing system; and

C) 0.1 wt.% To 30 wt.% Of a nitrogen-containing polymer selected from polyamide, polyimide, mixtures and / or

Copolymers thereof, in each case based on the total weight of fluoroelastomer and nitrogen-containing polymer, characterized in that the nitrogen-containing polymer is in the form of particles having an average particle size in the range of 0.15 to 70 μm and / or in fiber form with an average fiber diameter in the range of 0.15 to 70 pm.

2. Fluoroelastomer composition according to claim 1, characterized by a proportion of acting as an acid acceptor metal oxide, in particular to zinc oxide, magnesium oxide, calcium oxide, lead oxide (Pb0 / Pb304) of less than 1, 5 wt.% And / or by a proportion of acting as an acid acceptor Metal hydroxide, in particular of calcium hydroxide, of less than 1, 5 wt.% And / or by a proportion of acting as an acid acceptor metal salt, in particular hydrotalcite, calcium and / or magnesium stearate of less than 5 wt.%, In each case based on the total weight the

Fluoroelastomer composition.

3. Fluoroelastomer according to claim 1 or 2, characterized in that the fluoroelastomer is a radically curable, preferably a peroxide-curable fluoroelastomer.

4. A fluoroelastomer composition according to one or more of the preceding claims, characterized in that the nitrogen-containing polymer is selected from polymers having a melting temperature, determined according to ASTM D3418-08, or a

Decomposition temperature of more than 180 ° C.

5. fluoroelastomer composition according to one or more of

preceding claims, characterized in that the nitrogen-containing polymer at the curing temperature of the

Fluoroelastomer is solid.

6. fluoroelastomer composition according to one or more of

preceding claims, characterized in that the

Fluoroelastomer composition in the cured state

Volume swelling in 20% acetic acid after 168 h / 95 ° C, measured according to DIN ISO 1817, from 0 to 25 percent by volume, more preferably from 0 to 15 percent by volume, in particular from 0 to 10 percent by volume.

7. fluoroelastomer composition according to one or more of

preceding claims, characterized in that the

Fluoroelastomer composition in the cured state

Compression set after 168 h / 200 ° C, measured according to DIN ISO 815, from 0 to 70 percent, for example 1 to 70%, more preferably from 0 to 60%, for example 1 to 60%, in particular from 0 to 40%, for example 1 to 40%.

8. Process for the preparation of a curable

A fluoroelastomer composition according to one or more of the preceding claims comprising the steps:

A) providing a curable, preferably radically curable, in particular peroxide-curable fluoroelastomer;

B) providing a nitrogen-containing polymer selected from polyamide, polyimide, blends and / or copolymers thereof, wherein the nitrogen-containing polymer is in particulate form having an average particle size in the range of 0.1 to 70 microns and / or in fiber form having a mean fiber diameter is present in the range of 0.1 to 70 pm;

C) Mixing the curable fluoroelastomer with the nitrogen

polymer containing at a temperature which is less than the melting temperature or decomposition temperature of the nitrogen-containing polymer, whichever is lower, to form a polymer blend containing the curable fluoroelastomer and 0.1 wt% to 30 wt% nitrogen Polymer, based on the total weight of fluoroelastomer and nitrogen-containing polymer, and

D) adding a curing system, in particular a peroxide curing agent and a crosslinking coagent, to the

Polymer mixture at a temperature which is lower than the melting temperature or decomposition temperature of the nitrogen-containing polymer, whichever is lower, to form a curable fluoroelastomer composition.

9. Use of a fluoroelastomer according to one or more of claims 1 to 7 for the production of seals, in particular O-rings, frame seals, radial shaft seals, bellows, valve stem seals.

10. A seal comprising a fluoroelastomer composition according to

one or more of claims 1 to 7 in the cured state.

11. Use of a seal according to claim 10 for use in acidic media.